Theory of Parity-Violating Nonleptonic Decay

The simplest way of explaining the result $A\left({\Sigma }^{+}\right|n{\pi }^{+})=0\mathrm{}$ is to assume an effective parity-violating Hamiltonian of the form ${(\overline{B}\times B)}_{\mathrm{}\left(8\right)\mathrm{}}\times \pi$. With no further assumptions, this Hamiltonian predicts two sum rules which are closely related to the Lee-Sugawara triangle, and it imposes an isotopic-spin selection rule $\Delta T<\mathrm{}\frac{5}{2}$. The proposed coupling scheme is a consequence of several dynamical models, and the $\Delta T<\mathrm{}\frac{5}{2}$ rule is consistent with the data on $K\to 2\pi$.